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OLIVEUITE. 509 FIG. 607. ah 00° o' ee' 69° 10' vb 64 14 ma 46 15 vv 71 32 mb 43 45 va 90 0 mm' 87 30 ea 55 25 Combinations, em, enib, ema, emba. The faces e, a generally concave; m, convex and uneven. Cleavage. e, m, traces. Praeture conchoidal, uneven. Semi-transparent... opaque. Lustre vitreous, inclining to adamantine or resinous. Olive- green passing into blackish-green and brown. Streak olive- green. Brittle. II = 3*0. G = 4'1...4'38. In the matrass yields water. In the forceps melts easily before the blowpipe into a globule studded with prismatic crystals. On charcoal emits fumes of arsenic and melts into a brittle globule of arsenide of copper. Soluble in nitric acid and in ammonia. Is decomposed by potash, leaving a residue of oxide of copper. i Cu 3 As -f Cull, arsenic acid 40-66, oxide of copper 56-16, water 3-18. Part of the arsenic acid is sometimes replaced by phosphoric acid. Analyses of olivenito from Cornwall a by v. Kobell, b, c by Richardson, d, a = 4-135, e, g = 3-013, both by Hermann, / by Thomson, y, g = 4 - 378, by Hnmour:— a b c d e f y Arsen, ac. . . 80'7I 39-0 30-80 33-60 40‘50 40-61 34 87 Phosph. ac. . . 3'36 — — 6'0O 1-00 — 3"43 Cx. copper . . 60-43 56"2 50"C5 66 38 61"03 64'08 66'86 Protox. iron . — — — — 8 - 64 — — \Vater . . . 3’60 3-0 3’55 4-16 3-83 4‘41 3’72 In attached crystals, frequently acicular and capillary ; in fibrous, botryoidal and reniform masses having a drusy surface and a fibrous fracture; earthy. _ It is probably produced by the decomposition of fahlerz containing arsenic, which is some times found in the interior of the massive and earthy varieties of olivenite. Is found in Cornwall in the veins of copper ore in the mines of Huel Grorlnnd and Duel Unity near St. Day, and Tin Croft near Redruth, at Tyne head mine near Alston Moor in Cum berland. The massive and earthy varieties are found at Kams- dorf and Saalfeld in the Thiiringer Wald, Sehwatz and Kogel in the Tyrol, the Banat, Siberia, the Asturias, Chile. % 3